Elasticized leg and waist bands have gained increasing popularity in the areas of disposable applications, such as disposable diapers, feminine care products, adult incontinent products and hospital gowns.
A wide range of adhesive compositions are known and used in the construction of disposable articles. For example, it is well known that polyolefin based adhesives are suitable for the construction of diapers, particularly in the bonding of polyethylene films, or the like, to tissue or nonwoven substrates in the production of such articles. However, polyolefin based adhesives are not suitable for bonding of the elastic bands in these products because creep resistance is insufficient for such an application.
Accordingly, adhesives based on styrene such as styrene-isoprene-styrene (SIS) block copolymers or styrene-butadiene-styrene (SBS) block copolymers are used. Such flexible rubber based adhesives are the primary adhesive used for the bonding of elastic bands in the market today. However, these block copolymer adhesives lose most of their bond strength, resulting in adhesive bond failure, upon exposure to mineral oil or other oil based ointments which are often used on infants to treat skin rashes. As a result, the elastic leg bands may actually come loose from the diaper resulting in a break down of the inner leg cuff.
Polybutylene based hot melt adhesives, also a flexible adhesive product, have also been disclosed as useful for use in the attachment of elastic bands in nonwoven disposable products because of their flexibility and there resistance to oil. WO 97/39075.
It has suprisingly been found, in accordance with the present invention, that an adhesive prepared from a polymeric dimer fatty acid polyamide resin, in amounts of 70-100% of the adhesive composition, will provide bond strength for the attachment of elastic bands to disposable articles, while being resistant to exposure to mineral oil and oil based ointments. Polymeric fatty acid polyamides have been added to conventional rubbery block copolymers of the general formula A-B-A, such as SIS or SBS, in amounts of 1-20% to improve the heat and plasticizer resistance of the adhesive formulation. U.S. Pat. No. 4,419,494.
Accordingly, the adhesives disclosed herein find particular use to attach elastic bands in disposable items, particularly for leg or waist band closures on disposable diapers, adult incontinent products and other nonwoven articles.